This invention relates generally to shipping containers and more particularly to a new and improved shipping container that may be utilized with a standard pallet and is formed with a novel bottom structure as will be more fully described hereinafter.
In the packaging of bulk materials such as polyethylene pellets and other similar granular materials, it is known to provide an open shell structure having a plurality of top and bottom caps which are used to enclose the structure. The top and bottom caps may be banded in place on the structure to retain the cap in place and also to attempt to make the structure as leakproof as possible. An example of a construction of this type is shown in the U.S. Pat. No. 3,261,533, issued to E. F. Repking, on July 19, 1966. Structures of this type, while satisfactory for certain materials, would not necessarily be satisfactory for all material and must of necessity rely on the tightness of the banding strap around the top and bottom caps in order to obtain a leakproof container.
When designing bulk containers such as may be utilized with polyethylene pellets, it is desirous to be able to obtain high stacking strengths so that several containers may be stacked on top of each other in a warehouse. For this purpose it is often desirable to design the container shape in other than a rectangular shape such as for example an octagonal shape which has great structural strength due to the structural channels obtained by the eight vertical folds in the side of the octagonal container. Containers such as this are able to be utilized for greater stacking without having to rely on a large number of multiple plys formed on the side of the container to obtain the same effect.
One of the problems encountered in forming an octagonal container is in the formation of the bottom of the container. It is known to utilize standard flaps to form the bottom of octagonal containers, but such standard bottoms are generally not leakproof and generally not satisfactory for the handling of bulk granular material. Examples of such standard octagonal containers utilizing standard bottoms are shown in the U.S. Pat. No. 2,459,727, issued to H. B. Tillery, on Jan. 18, 1949, and the U.S. Pat. No. 1,864,081, issued to W. S. Marr, on June 21, 1932.
In order to obtain better leakproof properties in an octagonal container, variations of end cap structures have been attempted which interlock the end cap with the sides of the octagonal structure. One example of this type of construction is shown in the U.S. Pat. No. 2,357,093, issued to S. DeMian et al, on Aug. 29, 1944. End cap locking of this type, while being virtually leakproof, requires extensive setup time and costlier packaging material due to the increased size of the end caps required for the interlocking feature.
Other methods have been tried to make a leakproof octagonal or nonrectangular package as typified in the U.S. Pat. No. 1,221,900, issued to L. C. Palmer, on Apr. 10, 1917, wherein there is provided a separate flat sheet which is utilized as a top and bottom lid for the package with the sheet being sealed to the package by means described in the patent. In combination with this package, the fine granular materials such as powder may be packaged in a separate bag contained within the container in order to assure a virtual leakproof package. While such packages may be desirable and satisfactory for certain materials, they would not necessarily be satisfactory for today's packaging of large quantities of bulk granular material which may not only be packaged in the container, but may be stored at the warehouse in the same shipping container. That is to say the package typified by the Palmer patent must be virtually destroyed in order to remove the contents thereof since the top cap is not removable and replaceable back on the package as may be desired.
This feature of providing a removable top cap is designed into the container shown in the U.S. Pat. No. 2,077,173, issued to M. E. Holy, on Apr. 13, 1937, wherein there is provided a top and bottom cap which are formed out of flat sheets and which are positioned within the container and are held on the container by a plurality of flaps. The top cap in the subject patent is removable from the container without destroying the integrity of the container while the bottom flap is positioned within the container and is held in position by a series of lateral extensions which lock the bottom sheet in the container body. This type prior art container is undoubtedly satisfactory for relatively light loads of small articles such as individual ice cream cups or containers for which the container was designed, but would not necessarily be satisfactory for large quantities of granular material which have a tendency to work their way out of the package unless the package is made virtually leakproof.